MASTER OF DENTAL SURGERY (BRANCH I)repository-tnmgrmu.ac.in/5048/1/240102017elavarasan.pdf · FIXED...

EVALUATION OF ELEVATOR MUSCLE ACTIVITY USING

ELECTROMYOGRAPHY IN PATIENTS RESTORED WITH

FIXED PARTIAL DENTURE IN GROUP FUNCTION

OCCLUSION AND CANINE GUIDED OCCLUSION

A Dissertation submitted to

THE TAMILNADU DR. MGR MEDICAL UNIVERSITY

In partial fulfillment of the requirements for the degree of

MASTER OF DENTAL SURGERY

(BRANCH – I)

(PROSTHODONTICS AND CROWN & BRIDGE)

2014 – 2017

Certificate

This is to certify that Dr. S. ELAVARASAN, Post Graduate student (2014 -

2017) in the Department of Prosthodontics and Crown and Bridge, has done this

dissertation titled “EVALUATION OF ELEVATOR MUSCLE ACTIVITY

USING ELECTROMYOGRAPHY IN PATIENTS RESTORED WITH FIXED

PARTIAL DENTURE IN GROUP FUNCTION OCCLUSION AND CANINE

GUIDED OCCLUSION” under my direct guidance and supervision in partial

fulfillment of the regulations laid down by The Tamil Nadu Dr. M.G.R. Medical

University, Guindy, Chennai – 32 for M.D.S. in Prosthodontics and Crown & Bridge

(Branch I) Degree Examination.

Guided by Head of the department

Prof. Dr. K. VINAYAGAVEL, M.D.S., Prof. Dr. C. SABARIGIRINATHAN,M.D.S.,

Department of prosthodontics Head of the Department

Tamil Nadu Govt. Dental College &Hospital, Department Of Prosthodontics,

Chennai-600 003. Tamil Nadu Govt. Dental College &

Hospital, Chennai -600 003.

.

Head of the institution

PROF. Dr. B. SARAVANAN, M.D.S., Ph.D

PRINCIPAL

Tamil Nadu Govt. Dental College & Hospital,

Chennai-600 003.

DECLARATION

I, Dr. S. ELAVARASAN, do hereby declare that the dissertation titled

“EVALUATION OF ELEVATOR MUSCLE ACTIVITY USING

ELECTROMYOGRAPHY IN PATIENTS RESTORED WITH FIXED

PARTIAL DENTURE IN GROUP FUNCTION OCCLUSION AND

CANINE GUIDED OCCLUSION” was done in the Department of Prosthodontics,

Tamil Nadu Government Dental College & Hospital, Chennai 600 003. I have utilized

the facilities provided in the Government Dental College for the study in partial

fulfilment of the requirements for the degree of Master of Dental Surgery in the

speciality of Prosthodontics and Crown & Bridge (Branch I) during the course

period 2014-2017 under the conceptualization and guidance of my dissertation guide,

PROF. Dr. K. VINAYAGAVEL. MDS.,

I declare that no part of the dissertation will be utilized for gaining financial

assistance for research or other promotions without obtaining prior permission from the

Tamil Nadu Government Dental College & Hospital.

I also declare that no part of this work will be published either in the print or

electronic media except with those who have been actively involved in this dissertation

work and I firmly affirm that the right to preserve or publish this work rests solely with

the prior permission of the Principal, Tamil Nadu Government Dental College &

Hospital, Chennai 600 003, but with the vested right that I shall be cited as the

author(s).

Signature of the PG student Signature of the HOD

Signature of the Head of the Institution

TRIPARTITE AGREEMENT

This agreement herein after the “Agreement” is entered into on this day,

December 23, 2016 between the Tamil Nadu Government Dental College and

Hospital represented by its Principal having address at Tamil Nadu Government Dental

College and Hospital, Chennai-3, (hereafter referred to as, ‘the College’)

And

Dr. K. VINAYAGAVEL, M.D.S., aged 44 years working as Professor, in the

Department of Prosthodontics and crown and bridge at Tamil Nadu Government Dental

College and Hospital, Chennai-3 having residence address at No.15, Guru Kirpa

Apartments, G3, 4th Cross, United India Colony, Kodambakam, Chennai - 24 (herein

after referred to as the ‘Researcher and Principal investigator’)

And

Dr. S. ELAVARASAN aged 33 years currently studying as Post Graduate

student in the Department of Prosthodontics and Crown & Bridge, Tamil Nadu

Government Dental College and Hospital, Chennai-3 (herein after referred to as the

‘PG/Research student and Co- investigator’).

Whereas the ‘PG/Research student as part of her curriculum undertakes to

research on the study titled “EVALUATION OF ELEVATOR MUSCLE

ACTIVITY USING ELECTROMYOGRAPHY IN PATIENTS RESTORED

WITH FIXED PARTIAL DENTURE IN GROUP FUNCTION

OCCLUSION AND CANINE GUIDED OCCLUSION” for which purpose the

Researcher and Principal investigator shall act as Principal investigator and the College

shall provide the requisite infrastructure based on availability and also provide facility

to the PG/Research student as to the extent possible as a Co-investigator

Whereas the parties, by this agreement have mutually agreed to the various

issues including in particular the copyright and confidentiality issues that arise in this

regard. Now this agreement witness as follows:

1. The parties agree that all the research material and ownership therein shall

become the vested right of the college, including in particular all the copyright

in the literature including the study, research and all other related papers.

2. To the extent that the College has legal right to do go, shall grant to licence or

assign the copyright do vested with it for medical and/or commercial usage of

interested persons/entities subject to a reasonable terms/conditions including

royalty as deemed by the college.

3. The royalty so received by the college shall be equally by all the parties.

4. The PG/Research student and PG/Principal Investigator shall under no

circumstances deal with the copyright, confidential information and know how

generated during the course of research/study in any manner whatsoever, while

shall sole vest with the manner whatsoever and for any purpose without the

express written consent of the college.

5. All expenses pertaining to the research shall be decided upon by the Principal

investigator/Co-investigator or borne sole by the PG/Research student (Co-

investigator).

6. The College shall provide all infrastructure and access facilities within and in

other institutes to the extent possible. This includes patient interactions,

introductory letters, recommendation letters and such other acts required in this

regard.

7. The principal investigator shall suitably guide the student research right from

selection of the research topic and area till its completion. However the

selection and conduct of research, topic and area research by the student

researcher under guidance from the principal investigator shall be subject to the

prior approval, recommendations and comments of the Ethical Committee of

the college constituted for this purpose.

8. It is agreed that as regards other aspects not covered under this agreement, but

which pertain to the research undertaken by the Student Researcher, under

guidance from the Principal Investigator, the decision of the college shall be

binding and final.

9. If any dispute arises as to the matters related or connected to this agreement

herein, it shall be referred to arbitration in accordance with the provisions of the

Arbitration and Conciliation Act, 1996.

In witness whereof the parties herein above mentioned have on this the

day month and year herein above mentioned set their hands to this agreement in

the presence of the following two witnesses.

College represented by its Principal Guide

Witnesses

1. PG Student

2.

ACKNOWLEDGEMENT

I am extremely thankful my Chief Dr. C. SABARIGIRINATHAN,M.D.S.,

Professor and Head of the Department, Department of prosthodontics, Tamil Nadu

Government Dental College and Hospital, Chennai, I consider it my utmost privilege

and honor to express my most sincere and heartfelt gratitude for the valuable guidance;

he has given throughout my post graduation and at various stages of my dissertation.

My sincere thanks to Prof. Dr. B. SARAVANAN, M.D.S., Ph.D. Principal,

Tamil Nadu Government Dental College and Hospital for his kind help, valuable

suggestions in this study and permitting me to use all the facilities in the institution. I

also thank him for the valuable guidance he has given throughout the period of my post

graduate course.

I am extremely thankful and I consider it my utmost privilege to express my

sincere and heartfelt gratitude to my Guide PROF. Dr. K. VINAYAGAVEL. M.D.S.,

Department of Prosthodontics, TamilNadu Government Dental College and Hospital

for his valuable guidance, suggestions, encouragement, monitoring and support he has

given throughout the period of my post graduate course and at all stages of this

dissertation. Without his immense help this dissertation would not have come out in a

befitting manner.

My sincere thanks to Dr. A. MEENAKSHI, M.D.S., Professor, Department of

Prosthodontics, Tamilnadu Government Dental College and Hospital for her valuable

guidance throughout my study.

I am thankful to Associate Professors, Dr. P. Rupkumar, M.D.S.,

Dr. G. Sriramaprabu, M.D.S., Dr. M. Rajakumar, M.D.S., for helping me at

different stages of this study.

I am thankful to Assistant Professors, Dr.T.Jeyanthikumari, M.D.S.,

Dr.S.Vinayagam,M.D.S., Dr.J.Gandhimathi,M.D.S., Dr.V.Parimala,M.D.S.,

Dr.M.Kanmani,M.D.S., Dr.V.Harishnath,M.D.S., Dr.Preethichandran,M.D.S., and

Dr.SivaSakthiKumar,M.D.S., for helping me at different stages of this study.

I would like to extend my thanks to Prof. Dr. S. GOPINATHAN, M.D.,

D.M.,(Neuro). Director, Institute of NEUROLOGY, Madras Medical College & Govt

General Hospital, Chennai by permitting me to utilize the infrastructure in EMG study.

I am thankful to Dr.Kannan Vangiliappan Neurology Postgraduate for helping

me in the EMG study.

I thank Dr. S. SHYAM, M.D.S., for helping me, to carry out the statistical analysis

of the various test results.

I am thankful to Mr. P.M. Chakaravarthy VMC Dental Laboratory Chennai, for

assisting me in the laboratory works.

I owe my sincere thanks to all my Colleagues, Senior and Junior postgraduates

in the department for their constant encouragement and timely help.

Above all I thank the ALMIGHTY for giving me the strength and courage to

complete this monumental task.

CONTENTS

SL NO.

TITLE

PAGE NO.

1.

INTRODUCTION

1-2

2.

AIM AND OBJECTIVES

3

3.

REVIEW OF LITERATURE

4-30

4.

MATERIALS AND METHODS

31-45

5.

RESULTS

46-49

6.

DISCUSSION

50-59

7.

SUMMARY & CONCLUSION

60-61

9.

BIBLIOGRAPHY

62-70

8.

ANNEXURE

71-74

LIST OF ABBREVIATIONS

SL No. ABBREVIATION EXPANSION

1 EMG Electromyography.

2 CGO Canine Guided Occlusion

3 GFO Group Function occlusion

4 mm Millimetre

5 µvolt Micro volt

6 cm Centimetre

7 TMJ Temporomandibular joint

8 TMD Temporomandibular disorders

9 LED Light Emitting Diode

10 JVA Joint Vibration Analysis

11 MUAP Motor Unit Action Potential

12 FPD Fixed Partial Denture

13 OPG Orthopantomogram

14 IOPA Intra Oral Periapical Radiograph

LIST OF PHOTOGRAPHS

SL.NO

TITLE

1.

Materials and Armamentarium used during diagnostic stage.

2.

Materials and Armamentarium used during diagnostic mounting and face bow

transfer.

3.

Materials and Armamentarium used during Tooth preparation, Impression and

Temporization.

4.

Materials and Armamentarium used during Die preparation, Wax pattern

fabrication and Casting.

5.

Extra oral view

6.

Pre-OP Intra oral view

7.

Occlusal view - Maxillary Arch

8.

Occlusal view Mandibular Arch

9.

Diagnostic Impression

10.

Diagnostic Cast

11.

Diagnostic Articulation

12.

Lingual half of the Index is Positioned to check its Accuracy

13.

Gingival half of the Index is Positioned to check its Accuracy

14.

Lingual half of the index over the preparation to check Occlusal reduction

15.

Gingival half of the index over the preparation to check Labial reduction

16.

Tooth preparation & Retraction cord placement- Front view.

17.

Tooth preparation & Retraction cord placement- Occlusal view

18.

Final Master Impression & Alginate Impression for Temporization

19.

Working Cast for Provisionalization.

20.

Putty index for provisional restoration.

21.

Temporization.

22.

Die preparation in Master cast

23.

Facebow Transfer.

24.

Triple tray & Maximum Intercuspation Record

25.

Articulation done for fabrication of restoration.

26.

Wax Pattern – Occlusal view.

27.

Wax pattern for canine guided occlusion.

28.

Wax pattern for group function occlusion

29.

Metal Coping – Occlusal view

30.

Metal coping for canine guided occlusion

31.

Metal coping for group function occlusion

32.

Metal Trial in Patient mouth

33.

Metal trial – Occlusal view

34.

Finished metal ceramic FPD with group function & canine guided occlusion

35.

Metal ceramic restoration for group function occlusion.

36.

Metal ceramic restoration for canine guided occlusion

37.

Non-Working Interferences are relieved in Articulator

38.

Metal Ceramic restoration checked in patient mouth at maximum Intercuspation

39.

Metal Ceramic Restoration in Patient mouth-Occlusal view

40.

Group function occlusion achieved in working side

41.

Non-Working Interferences was checked and relieved.

42.

Canine guided occlusion achieved in working side

43.

Electromyographic Unit

44.

Electromyographic Software

45.

Positive, Negative & Ground Electrodes

46.

EMG 4 Channel Amplifier Box

47.

Placement of surface electrodes to record Masseter muscle activity

48.

Placement of surface electrodes to record Temporalis muscle activity

49.

Base line Readings Before Activity

50.

EMG recordings during movement

LIST OF TABLES

S. No

TITLE

Page No

1.

EMG Values of Masseter and Temporalis muscles

during Clenching in Group function and Canine guided

occlusion on the Restored side.

36

2.

EMG Values of Masseter and Temporalis muscles

during Lateral Excursion in Group function and Canine

guided occlusion on the restored side.

36

LIST OF BAR DIAGRAMS

S. No

TITLE

Fig.1

Comparison between Group function and Canine guided

Occlusion of Masseter muscle during clenching and lateral

Excursion towards the restored side.

Fig.2

Comparison between Group function and Canine guided

Occlusion of Temporalis muscle during clenching and lateral


Fig.3

Comparison of Group function and Canine guided occlusion

during Maximum Voluntary clenching of Masseter and

Temporalis.

Fig.4

Comparison of Group function and Canine guided occlusion

during Lateral excursion of Masseter and Temporalis.

ABSTRACT

Introduction: There is no way to isolate one part of the Stomatognathic system and

ignore the other parts. If one part gets affected the other parts prone to suffer.

Establishing the optimum oral health cannot be achieved unless all the functional

components are in harmony with each other. We should establish a harmonious inter-

relationship of all parts, without excessive stress, since stress induces deterioration of

the weaker components of the system. Group function and Canine guided occlusion

have been used in the study.

Keywords: Electromyography, Canine guided occlusion, Group function occlusion,

Elevator muscle activity.

Aim: The purpose of this study was to determine which of the two occlusal schemes

causes a greater reduction in elevator muscle activity (Masseter, Temporalis) and

decrease of muscle tension in lateral movements of mandible using EMG.

Materials and methods: 10 Partially edentulous patients were selected as per

predetermined criteria. Each patient was restored with two fixed partial dentures with

Canine guided occlusion (Group A) and Group function occlusion (Group B) with an

interval of one week. After cementation, surface EMG recordings were made in

maximum voluntary clenching and lateral excursion for Group function occlusion and

Canine guided occlusion. The results were then statistically analyzed.

Results: Significant reduction of elevator muscle activity was observed in lateral

excursion in patients restored with Canine guided occlusion, but it was nearly the same

for clenching in both the occlusal patterns.

Conclusion: It was concluded from the above results that, when an entire occlusion is

to be restored, reestablishment with canine guided occlusion is preferred when

remaining canines are present with good periodontal support. The EMG values

obtained in this study can be taken as base line data for future studies.

Introduction

1

INTRODUCTION

United we stand, divide we fall. As we know the harmonious

functioning of the stomatognathic system is not possible without the trio of TMJ,

muscles and the teeth going hand in hand. Disturbance in one factor leads to a chain of

events eventually leading to the collapse of the entire stomatognathic system.

Though treating TMJ disorders and muscle dysfunction seemed to be a

vague area of diagnosis and treatment, the advent of medical facilities like

Electromyography, T scan, Joint Vibration Analysis (JVA) has helped us a lot to locate

the site causing the problem. Electromyography is nowadays being used increasingly in

research and clinical dentistry.

There is an elegant synchrony in the input delivered to the masticatory

system by means of proprioception and perception which in turn send signals to the

muscles, teeth and TMJ through the pathway of motor responses. Perception relates to

the sensory innervation of the periodontal membrane, epithelial surfaces of the oral

cavity, muscles of the tongue and muscles of mastication and TMJ. Any break in this

vicious cycle leads to dysfunction in the stomatognathnic system.

The extent and number of occlusal contacts and their periodontal

mechanoreceptors play a keyrole as the peripheral occlusal control of the elevator

muscles. It defines the electrical muscle activity, bite force, jaw movements and

masticatory efficiency.

Anterior guidance is mandatory for the integrity of anterior teeth and the

long time stability of the posterior teeth. Two conflicting concepts on occlusion has

gained popularity nowadays which include Group function and Canine Guidance.

Introduction

2

In the Glossary of Prosthodontic terms, canine protection is defined as

“a form of mutually protected articulation in which the vertical and horizontal overlap

of the canine teeth disengage the posterior teeth in the excursive movements of the

mandible.” Group function is defined as “multiple contact relations between the

maxillary and mandibular teeth in lateral movements on the working side”1.

According to Beyron who favoured the concept of Group function

occlusion, exhibits attrition and abrasion as a positive adjustment as they distribute the

occlusal stress and direct them in a more axial direction2.

D'Amico claimed Canine Guided occlusion is more advantageous as

Canine has a uniquely sensitive feedback mechanism leading to involuntary reduction

in jaw muscle tension and force application. In lateral excursions canine, causes a break

in tension of temporal and masseter and act as a natural stress breaker3.

So a study is undertaken to find out which of these two types of occlusal

guidance causes a greater quantitative reduction in the activity of elevator muscles

(Masseter, Temporalis) using Electromyography.

Aim and Objectives

3

AIM AND OBJECTIVES

AIM:

The aim of the study attempts to find out the elevator (Masseter, Temporalis)

muscle activity using Electromyography with the help of surface electrodes when the

patients are restored with fixed partial dentures in group function occlusion and canine

guided occlusion.

OBJECTIVES:

1. To observe and compare the EMG values of the Masseter during clenching in

patients restored with Fixed partial dentures in group function occlusion and

canine guided occlusion.

2. To observe and compare the EMG values of the Masseter during lateral

excursion in patients restored with Fixed partial dentures in group function

occlusion and canine guided occlusion.

3. To observe and compare the EMG values of the Temporalis during clenching

in patients restored with Fixed partial dentures in group function occlusion and

canine guided occlusion.

4. To observe and compare the EMG values of the Temporalis during lateral

excursion in patients restored with Fixed partial dentures in group function

occlusion and canine guided occlusion.

Review of literature

4

REVIEW OF LITERATURE

ROBERT E. MOYERS (1956)4 observed about the neurophysiologic regulation of

centric relation and other jaw positions. He found that the muscles alone could not

establish so a precise mandibular position, while muscles contracting. But the

maximum intercuspation of teeth makes mandibular positions possible for the brain to

learn quickly. The only reflex determining mandibular position present at

birth is the postural position of the mandible . Centric relation is

learned after the eruption of teeth. It is the first learned reflex

determining the occlusal position of the mandible after expedient

mechanisms for avoiding occlusal disharmonies. They are forgot ten

when the source of the afferent impulses prompting them is removed.

Centric relation in the edentulous patient is determined largely by the

muscle proprioceptors, and thus presents slightly different problems in

registration.

J.C. HICKEY (1957)5 measured the muscular activity for various jaw movements

and the total electrical activity of the different muscles was compared on the time

basis. He concluded that external pterygoid and suprahyoid musc les were

responsible for opening movement. Masseter and temporalis were

responsible for closing movement. Left external pterygoid muscles

were responsible for movement of mandible to right and right external

pterygoid muscles for the opposite side. External pterygoid muscles on

both sides were responsible for the protrusion of mandible.


5

ANGELO D’AMICO (1961)3 conducted a study on attrition in the prewhite

California Indians. He stated that the natural vertical and horizontal overlap relation

of the upper cuspids is not strictly a mechanical block. Their function is more than a

mechanical guidance of the mandible and mandibular teeth into centric occlusion. If

the upper cuspids are in the ideal functional relation, attrition of the occlusal surfaces

of premolars and molars is almost completely eliminated.

JERRY GARNICK et al (1962)6 conducted a study on the rest position of

the mandible clinically and electromyographically in 20 adult subjects

with functionally adequate occlusion. Three commonly used methods

for the clinical determination of the vertical relation of rest position

gave adults that were not significantly different statistically. The

average inter occlusal distance was about 1.7 mm clinically. A graded

instrument was used to measure the amount of closure of the jaws from

an opening posit ion. The instrument was used in combination with

EMG recordings of the anterior and posterior parts of temporal is and

masseter muscles and the anterior parts of the digastric mu scles. The

clinically observed rest position was located in a space of more than

minimal [resting] muscle activity in 13 of 20 subjects.

PERRY C. ALEXANDER (1963) 7 analysed about the cuspid protective

occlusion and concluded that

1. The balanced occlusion theory is a valid in relation to the

concept of physiologic, biologic, histologic and clinical

evidence.


6

2. Role of canine tooth was to function in union along with the

remaining teeth.

3. Proprioceptive response of the periodontal membrane of canine

teeth is not more sensitive than those of periodontal memb rane

of other teeth.

4. ‘Building up’ of the maxillary canine tooth so that it will

function alone in eccentric positions is contraindicated

5. Loss of vertical dimension based only on the attri tion of teeth in

prehistoric skulls is invalid in view of the well -documented

evidence supporting the continuous eruption theory by

GOTTLIEB and the relative stability of the vertical relation of

rest position as supported by cephalometric, cl inical and

electromyographic studies.

6. Development of an edge-edge occlusion as proposed by

D’AMICO was unacceptable as it refuses the concepts of

relative stability of the rest vert ical dimension and the

continuous eruption theory.

SYLVAN SCHIRESON (1963) 8 outlined an approach to rational

therapy of some problems encountered in periodontally involved

mouths. These problems include food impaction into the gingival

margins and pappilae, and loosening of t eeth due to periodontal

traumatism. He concluded that the periodontal disease and its sequela e,

the loss of teeth were not due to deviate from nature’s plan. Primitive

man had the same problems has does modern man. The therapeutic


7

approach should attempt to l imit towards the treatment of disease and

its causes.

LAWRENCE A. WEINBERG (1964) 9 recorded 100 dentulous subjects

cinematically to investigate the relationship between the occlusal

pattern, centric relation, centric occlusion, and temporomandibular

joint dysfunction. In that 81 percent exhibited lateral working s ide

cuspal contact and only 19 percent had a canine-protected occlusion. A

2 mm. discrepancy between centric relation and centric occlusion was

found in only one subject of the working side contact group, whereas

more than half of the canine-protected group had this degree of “h it

and slide.” He suggested that the possibil ity of an association between

a canine-protected occlusion and large discrepancies between centric

relation and centric occlusion.

CHRALES R. JERGE (1964) 1 0 presented a hypothesis concerning the

nervous mechanism subserving cyclic jaw movements. Data was

obtained from 46 experiments and the animals were domestic cats.

Experiment consisted of recording the electrical activity of individual

cells in various parts of the trigeminal complex from an extra cellular

position. The craniotomies were performed with animals in stereotaxic

instrument.

The fundamental mechanism underlying cyclic jaw motion

appeared to be the interaction of jaw closing muscle proprioceptors and

intraoral pressure receptors of the teeth and soft tissue. The concept of

two interacting dissimilar reflexes did not rule out the possibility of


8

reciprocal innervations in classical sense. The suggested mechanism of

jaw muscle interaction and that of reciprocal innervations were

compatible. Recent work o f Kawamura proved that, rec iprocal

relationships may exist

PERRY C. ALEXANDER (1967)1 1 evaluated the two theories of

occlusions with clinical findings about the denti tions. The difference

between these two theories was the treatment of the maxillary canine

teeth. The canine function theory believed that the canine teeth support

the forces of mastication during eccentric mandibular movements and

balanced occlusion theory believed that the forces of mastication must

be supported by as many teeth as possible during eccentric mandibular

movements. The canine function theory claims that the periodontal

ligament of the canines has a “protective mechanism” capable of

protecting the periodontium from periodontal breakdown due to the

horizontal forces. The clinical evidence presented does not support this

claim. He suggested that the dentition should be treated according to

the principles of the balanced occlusion theory.

PETER SCHAERER et al (1967)1 2 evaluated the interrelationship

between the occurrence of tooth contacts and the electromyographic

(EMG) activity during mastication in habitual occlusion, and after the

insertion of a balancing side cuspal interference. They concluded that

the EMG response during masti cation was the same for the different

types of tooth contacts. Tooth contacts were a part of the reflex

mechanisms controlling movements of the mandible and muscle


9

contractions. These masticatory mechanisms were influenced by

pressure- and touch-sensit ive receptors when tooth contact occurs,

regardless of where and in what maxillomandibular relationship they

take place.

ROBERT R. SCAIFE et al (1969)1 3 investigated the natural

occurrence of cuspid guidance in eccentric positions. 1,200 patients

were examined to determine the natural incidence of a cuspid protected

occlusion. The influence of the maxillary cuspids was observed in

centric occlusion and in protrusive, left , and right lateral excursive

positions. Bilaterally protected occlusion was f ound in 57 percent of

the subjects, 16.4 percent had a unilateral cuspid protection, and 26.6

per cent had no evidence of this phenomenon in lateral excursions. In

protrusive movements, 99.4 per cent of the subjects lacked a cuspid

protection. They concluded that the natural occurrence of a cuspid

protective mechanism was relatively large (57 per cent) but by no

means overwhelmingly predominant. The results of this study showed

factors both favorable and unfavorable to the cuspid protection theory

and group function theory.

CHARLES H. GIBBS et al (1971) 1 4 focused on the results of jaw

motion studies in relation to two objectives .The first objective was to

provide an accurate and extensive study of jaw motion and

maxillomandibular relationship during chewing. The second objective

was to determine the manner and degree that differing states of

occlusion affect jaw motion during chewing. Jaw motion data was


10

obtained from 12 subjects: 4 from normal occlusion, 4 with obvious

malocclusions. The paths of motion of condyles are quite similar for

subjects with “normal occlusion and mal occlusions. The closed

position repeatability is ranging from 0.01 -0.06 inch.

TIMOTHY J O’ LEARY et al, (1972) 1 5 assessed the mobility of teeth

in 30 maxillary quadrants of each of two gro ups of subjects ie., cuspid-

protected and group function occlusions . They found that the mean

mobility of teeth was greater with cuspid protected lateral movements

than in teeth with group function leads . Cuspid protection may be

physiologic for many people but the practice of altering occlusal

relations to establish a cuspid protection as prophylactic is open to

question. They suggested that changing the occlusion from group

function to canine protection may be deleterious to the periodontium.

ROBERT J. CRUM et al (1972)1 6 This review of the literature reveals

the discrete sensitivity that exists in the separate components of the

masticatory system. The function o f the masticatory system is

dependent upon the input of the neural system by proprioception and

perception. A defect or non integration of the proprioceptive or

perceptive input may result in poor function or pathologic changes to

parts of the system. The succes s or failure of a prosthodontic treatment

is also dependent upon the integration of proper proprioceptive

feedback and motor responses. They observed that the anterior teeth

were more sensitive than the posterior teeth . This shows the importance

of the incisal guidance in oral rehabilitation. They also observed that


11

the anterior and posterior teeth were more sensitive to lateral forces

than to the axial forces. The lower thresholds to lateral f orces may be a

protective mechanism.

D.BLAKE McADAM (1976)1 7 discussed tooth loading and cuspal

guidance in canine and group function occlusio ns. He concluded that

Canine guidance and group function occlusions were considered

normal. When the entire occlusion is to be restored, either occlusal

scheme will serve adequately. When small portion of occlusion is to be

restored, the restoration must be consistent, with the existing occlusal

scheme.

DAVID C. MCNAMARA (1977)1 8 investigated the neuromuscular

effects of tooth contact at the physiologic median occlusal position was

conducted before and after adjustments of the occlusion. 18 patients

with the history of disturbances in the masticatory system, but whose

painful symptoms had subsided, were observed before and after

occlusal adjustments. 9 patients with missing teeth restored with fixed

partial dentures and occlusal adjustments were done. Another group of

9 subjects with normal occlusions were used as controls. EMG study of

the bilateral temporal and masseter muscles enabled quantification of

two reflex parameters, the EMG silent period duration, and the

mechanical latency of the jaw-opening reflex. Phase-plane traces of

jaw- closing velocity as a function of position disp layed the

repeatability of the median occlusal position. The statistical analysis

disclosed that the mean duration of EMG silent periods and latency of


12

the jaw-opening reflex were significantly reduced following the

treatment procedures. Within the limits of this study it was concluded

that the described occlusal adjustments will reduce the masticatory

reflexes evoked at median occlusal position to within the range of

normal subjects. Furthermore these changes can be monitored by

electrophysical methods.

STEPHEN P. BRODERSON (1978)1 9 showed that the relationship

between the maxillary and mandibular anterior teeth is the most

important factor in the restoration and maintain ence of the ideal

occlusion. The anterior teeth occlusion is the key to developing an

"ideal" occlusion. The anterior teeth protect the posterior teeth by

disoccluding them in eccentric movements, and the posterior teeth

protect the anterior teeth by receiving most of the forces of closure in

centric position. The anterior guidance is a result of both anterior

tooth position and condylar border movements; both factors must be

considered in the creation of an anterior guidance.

GARY ROBERT GOLDSTEIN (1979)2 0 conducted a study to

determine the patterns of lateral occlusal excursions from the maximum

intercuspal posit ion (centric occlusion) and to relate with a periodontal

index. He concluded that the teeth of mouths having canine -protected

occlusions had lower mean periodontal disease index scores than the

progressive disclusion or group function. Also, the canines and the

molars in the canine-protected subjects showed lower mean periodontal

disease index scores than their counter - parts in the progressive

disclusion or group function.


13

ALAIN WODA et al (1979)2 1 A review of the literature on occlusal

contacts emphasizes the following points. Contacts in centric occlusion

do not correspond to any ideal occlusal diagram. Canine protection and

group function appear to correspond to two successive states of the

evolving dentition under the effect of abrasion. In most lateral

occlusions, two maxillary teeth, of which one is the canine, were

involved.

ARTURO MANNS et al (1979) 2 2 studied the relations between EMG,

force, and muscular elongations during submaximal isometri c

contractions of the masseter muscle measuring from 7mm to almost

maximal jaw opening. EMG was recorded with superficial electrodes

and bite forcerecorded with the gnathodynamometer. Results showed

that there was for each experimental subject a physiolog ically optimum

muscular elongation of major efficiency where the masseter muscle

developed highest muscular force with least EMG activity.

ROBERT L. DICKSON (1980) 2 3 discussed the concepts of anterior

disclusion such as the mechanical elements of a pair of discluder teeth,

discluder dynamic interaction between these elements, and the

guidance without causing undue stress on the grinding teeth

themselves. A discluder study board was constructed to analyze the

dynamic interaction between a pair of discluders. He concluded that ,

when there was a centric interference prior t o equilibration, the dentist

can determine whether to grind on the upper or lower tooth of a

discluding pair. Precise shaping of the functioning surfaces of the


14

discluder comes about naturall y. The common problem of “loosing the

guide” is eliminated. When using the rules presented here, the final

canine l ift will impart minimum forces to the discluder periodontium.

JOHN D. RUGH et al (1981)2 4 Revaluated the relationship of

jaw muscle activity, rest vert ical dimension, and clinical rest position.

The investigation was done in 10 subjects using EMG. The vertical

dimension of minimal muscle activity ranged from 4.5 – 12.6 mm with

an average of 8.6mm. Minimum muscle activity levels ranged from 1.1

– 1.8 µvolt. The mandibular position of 1 -3 mm of inter occlusal

distance measured phonetically referred to as ‘clinical rest posit ion’

and physiologic rest position. The results of this study suggest that this

position is not one of rest. In the upright position, some jaw muscles

must be in slight contraction to maintain the clinical rest position.

KEITH E. THAYER et al (1981)2 5 described a technique where metal

canine risers were attached to the l ingual surface of maxillary canine

teeth with acid-etch composite resin. They selected a patient with the

chief complaint of grinding and clenching of his teeth. Two years

postoperatively the patient was remains comfortable. The bruxing and

clenching habits had been eliminated, and the patient was functioning

properly.

WILLIAMSON et al (1983)2 6 compared the effect of canine guidance

and group function on the EMG activity of the masseter and anterior

part of the temporal muscles. The electrodes to the temporal muscles

were placed 1 inch posterior and 1 inch supe rior to the outer canthus of


15

eye. For masseter muscles it was determined by palpation, and they

were placed on the body of the muscle midway between origin and

insertion they concluded that , i t was not the contact of the canines that

decreases the activity of the elevator muscles, but the elimination of

the posterior contacts.

J. D. RUGH et al (1984)2 7 recorded nocturnal bruxism using EMG in

the subjects in whom experimentally defl ective occlusal contacts were

placed. The results of the study and the studies of Kardachi et al. and

Bailey and Rugh suggest that occlusal factors have little, if anything,

to do with the levels of nocturnal bruxism. This conclusion is in sharp

contrast to the common clinical assumption that nocturnal bruxism is

caused by occlusal conditions and can be eliminated through occlusal

adjustment.

RONALD J. SHUPE et al (1984) 2 8 studied the effect of different

occlusal guidance on jaw muscle activity. The occlusal schemes were

developed in a single maxillary heat cured acrylic resin occlusal splint

with minimal palatal coverage and a minimal increase in vertical

dimension of occlusion. The effect of each guidance on integrated

EMG activity of the masseter and temporal muscles is measured during

clenching, guiding and chewing. Results suggest that canine protected

guidance should be considered when restoration of occlusal guidance is

required so that the forces generated to posterior teeth are reduced.

J.W.C. Mac DONALD et al (1984) 2 9 described the relationships

between EMG activity in the jaw-closing muscles and the location,


16

area, and direction of effort applied to specific contact points, some of

which were selected to simulate clinical conditions. They concluded

that vertical clenching efforts in the natural or simulated inter cuspal

position generally showed the highest muscle activit ies for all the

muscles recorded. When the contact point moved posteriorly along the

arch from incisors to molars, the activity in the ipsilateral temp oral

muscles was seen to increase, while the activity in the ipsilateral

medial pterygoid and the masseter muscle. When the size and number

of contacts were increased anteriorly, a generalized increase in muscle

activity was seen. The same trend occurred posteriorly.

U.C.BELSER et al (1985)3 0 measured the physiologic behaviour when

a naturally acquired group function was changed into canine guidance,

and then into a hyper balanced occlusion. When a naturally acquired

group function was temporarily and artificially changed into a

dominant canine guidance, a significant general reduction of elevator

muscle activity was observed when subjects exerted full isometric

tooth-clenching efforts in a lateral mandibular position. The results

suggest that canine protected occlusions do not significantly alter

muscle activity during mastication but significantly reduce muscle

activity during parafunctional clenching. They also suggest that non -

working side contacts dramatically alter the distribution of muscle

activity during parafunctional clenching, and this redistribution may

affect the nature of reaction forces at the temporomandibular joints.


17

Y. YAMADA et al (1985)3 1 analysed the electromyograms in clinical

dentistry. A neurophysiologic real – time data acquisition and analysis

system with a versatile hardware / software combination to be applied

in clinical dentistry is introduced. Its application in the clinical

environment, allowed the analysis of jaw reflexes and the generation of

hard copy output in approximately 31/2 minutes. Such a system

provides the basis for advanced diagnostics in dentistry.

Electromyography (EMG) is used increasingly as a research tool, as

well as in clinical dentistry. The study of reflex responses can provide

information about the excitabil ity of alpha and gamma motor neurons

of the masticatory muscles.

WILLIAM W. WOOD (1987)3 2 said that there was a direct

relationship between integrated electromyographic activity and tension

in the muscle during isometric tasks. Surface electrodes are generally

regarded as satisfactory for recording global activity of the muscle, but

they also pick up some activity from surrounding muscles. Even so,

surface electrodes have been shown to be effective for recording from

both superficial and deep masseter muscles and superficial parts of

both anterior and posterior temporal muscles. He reviewed the actions

of the major muscles of mastication during clenching tasks in centric

occlusion and eccentric jaw positions, mandibular opening and

unilateral chewing.

He concluded that ,


18

1. Elevator muscles demonstrate maximum activity. Whenever

bilateral occlusal contacts occur during clenching in inter cuspal

position.

2. Elevator muscles are activated together in the inter cuspal zone of

tooth contact during chewing when the occlusal contacts are

balanced bilaterally in this inter cuspal position.

3. Increasing the number of eccentric tooth contacts increases muscle

activity during chewing and clenching.

4. Medical pterygoid muscle action is enhanced during mandibular

closing.

5. Inferior pterygoid muscle contributes to forward and lateral

bracing of the condyle of the mandible.

ARTURO MANNS et al (1987)3 3 performed an EMG study between

two types of occlusal guidance : group function and canine guidance.

Full coverage occlusal splints were made with normal function of the

stomatognathic system. Left and right side integrated EMG recordings

were made of masseter and temporal muscles during static and dynamic

maximal contractions. The results showed and EMG reduction of the

elevator muscles with group function relative to their activity in

centric occlusion. With canine guidance the reduction is much greater,

mainly in the temporal muscle of the mediotrusive side. With canine

guided occlusion the pressure is concentrated in a smal l periodontal

surface area. Thus a small amount of pressure or isometric contraction

of the elevator muscles is needed to activate the periodontal receptors.

The clinical implications of this study suggest the use of canine


19

guidance in laterotrusion for therapy with full coverage occlusal

splints.

In the lateral posit ion with group function, the pressure is

distributed over a larger periodontal surface. This allows for greater

pressure or increased isometric elevator muscle contraction to reach

the tolerance level, which in turn releases the inhibitory influence of

the periodontal mechanoreceptors.

With canine-guided occlusion, the pressure is concentrated in a

small periodontal surface area. Thus a small amount of pressure or

isometric contraction of the e levator muscles is needed to activate the

periodontal receptors.

Mechanosensitivity thresholds of the teeth demonstrate that the

canines possess a much higher pressure sensitivity and st ereotactility

in other words, an essentially finer sensitivity -than posterior teeth.

Because these are the first teeth to contact in lateral movements, the

canines can take over regulatory functions and act as an important

protective mechanism against excessive forces.

SHOJI KOHNO et al (1987)3 4 described a method of measu ring

condylar and incisal angles in an effort to develop criteria for anterior

guidance in clinical practice. They suggest that the inclination of the

sagittal incisal path, which is transferred to the incisal table of an

art iculator as anterior guidance, should be equal to the inclination of

the patient’s condylar path. It is of course possible to make the incisal

path steeper than the condylar path to some extent; however, it should


20

not be made more than 25 degrees steeper. Similarly, the incisal path

should not be much flatter than the condylar path.

GAR S. GRAHAM et al (1988)3 5 conducted a study and compared the

canine guidance with first molar guidance to determine whether canine

guidance is unique in its effect on masticator y muscle EMG activity

during lateral movement and lateral excursive position clenching. They

concluded that the EMG activity of the masseter and anterior part of

the temporal muscles was reduced with canine guidance and also in

first molar guidance during lateral excursive movement a nd excursive

position clenching.

ARTURO MANNS et al (1989) 3 6 conducted a study to determine the

influence of variation in anterioposterior occlusal contacts on

electromyographic activity. A full maxillary stabilization splint

divided into three pairs of occlusal bilateral blocks was made. The

EMG activity of masseter and temporal muscles was recorded with

surface electrodes during maximum voluntary clenching in centric

occlusion. The results of this study suggest that the use of blocks with

nearly equivalent periodontal surface areas allows more accurate

differentiation between the biomechanics and neurophysiologic factors

LINDA J. THORTAN (1990) 3 7 reviewed the historical philosophies

and development of group function and canine guidance. Anterior

guidance, which can be categorized as group function or canine

guidance, is essential for esthetics, phonetics, and mastication. There

is no scientific evidence that supports one occlusal scheme over the


21

other. Where anterior guidance must be re established or where it

changes, there currently appear to be more authorities who favo ur

canine guidance over group function.

CARL G. GLASER et al (1991)3 8 described the use of etched

porcelain veneers in the treatment of a patient with a craniomandibular

disorder. The restoration of a progressive delayed disocclusion on

periodontally healthy canines by etched porcelain onlays had been

presented as a suitable treatment alternative to interrupt bruxism and

reverse destructive occlusal neuroses.

RANDALL C. DUNCAN et al (1992)3 9 made a study to determine

whether a decrease in intraoral sensory afferent discharge significantly

altered the onset of the jaw-unloading reflex using EMG. They placed

the bipolar surface electrode parallel to muscle fib res with

interelectrode distance of 2 cm. Line connecting outer canthus of eye

and the angle of mandible was used as guide in placing electrodes on

masseter muscle, with most inferior electrode 1 cm from mandibular

inferior border. Electrodes were placed on temporal muscle as close to

hairline as possible. Ground electrode was placed at the ipsilateral side

of the mastoid region.

M. M ALSAWAF et al (1992)4 0 assessed the influence of dynamic

tooth guidance and the influence of change in vertical dimension on the

recording of mandibular movements tracing, measuring, and comparing

the path of hinge axis of the condyles in subjects with and without TMJ

clicking through opening, protrusive, and lateral excursion movements.


22

The data gathered through computerized tracing of all subjects revealed

no significant difference in the mean angles of condylar guidance

regardless of whether the craniomandibular contact was an art iculation

of natural teeth or an articulation of maxillary natural teeth against a

tray clutch. Therefore, within the parameters of this investigation,

there was no evidence to support the notion that either the change in

vertical dimension or the influence of the dynamic interarch tooth

guidance reflected a significant alteration in the recordings of condylar

path travel.

BAKKE M. (1993)4 1 analysed the physiology and action of mandibular

elevators, with emphasis on the temporalis and masseter muscles, and

the effect of the dental occlusion on their function. He concluded that

the pathogenesis, the type of muscular performance associated with the

development of fatigue, discomfort, and pain in mandibular elevators

seems to be influenced by the dental occlusion. The e xtent of occlusal

contact clearly affects electric muscle activity, bite force, jaw

movements, and masticatory efficiency. Occlusal stabil ity keeps the

muscles fit, and enables the masticatory system to meet its functional

demands.

L. ABD Al-HADI (1993)4 2 conducted a study to estimate the

prevalence of temporomandibular disorders (TMD) among a population

group of nonpatients and to correlate their different symptoms with

certain occlusal parameters. Survey included 600 women and men


23

between 18 and 22 years of age. Horizontal overlap value was

determined by a dial caliper gauge. Presence of non - working contacts

was detected by dental floss. Eccentric lateral occlusion was studied.

They concluded that , TMDs were prevalent on the chewing sides. A

low occurrence of TMD was found in Class II Divisio n 2 patients.

TMDs were low in the canine-protected occlusion. TMDS were

associated with an increased incidence of non working side contacts

and also in class II division I patients and in group function occlusion.

A.C. AKOREN et al (1995) 4 3 they conducted a study to investigate

occlusal schemes (canine guidance and group function) in relation to

masticatory muscle activity. It was performed on 30 subjects, 15 with

canine guidance and 15 with group function. Bilateral

electromyographic recordings of masseter and anterior temporal

muscles were obtained by surface electrodes during gum chewing and

sliding laterally from centric relation while the teeth were in contact .

They concluded with the Observation of the gum chewing

electromyograms disclosed a narrow chewing model with canine

guidance and a wide chewing model with group function. In both

occlusion groups, during lateral sliding, the anterior temporal muscle

showed more activity than the masseter muscle. However, this activity

was least in the case of canine guidance occlusion. They suggested that

both occlusal schemes could be used for the treatment of subjects who

have lost their natural occlusion but, in case of the healthy canine teeth

with good support, canine guidance occlusion will be advantageous.


24

G. L. BORROMEO et al (1995)4 4 conducted a study using EMG to

investigate the effects on masseter muscle function of interocclusal

devices constructed to provide either balanced and unbalanced group

function or canine guidance in normal subjects. They concluded that,

no difference was found between the different subjects.

VIRGILLIO F. FERRARIO et al (1996) 4 5 analyzed the maximum

opening and mandibular lateral border movements in 165 patients with

a considerable lateral deviation in maximum opening. Mandibular

movements were measured with a kinesiograph. Half of men and

women had a deviation in maximum opening toward the right side.

Deviation toward the left side was found in 26 men and 40 women. The

results of this investigation underline the importance of dental

guidances in the mandibular movements: protection of the occlusal

surfaces from abnormal and protection of the temporomandibular joint .

The results may be explained by a correlation between the insufficient

lateral protection and a temporomandibula r mandibular joint

dysfunction.

TAKAHIRO OGAWA et al (1996) 4 6 demonstrated the characteristic of

masticatory movement related to the inclination of the occlusa l plane

in dentate subjects. No significant correlation was found between the

inclination of the occlusal plane and the closing path during tapping,

there was a significant correlation between the inclination of the

occlusal plane and the closing path duri ng masticatory movement

outside of the intercuspal range. The incisal path approached the


25

occlusal plane maintaining a perpendicular relationship in the sagittal

plane. These results serve as a background of the functional occlusal

plane.

RIAD E. YOUSSEG et al (1997)4 7 compared the habitual masticatory

patterns in men and women using a custom computer program.

Masticatory cycles of 20 normal men and 17 women were examined

during mastication of a constant bolus at a sampling rate of 500 Fps.

They observed that men had significantly shorter chewing cycles, with

faster velocities than women and men used significantly g reater

chewing force than women, though their EMG activity levels were

equivalent. The total duration of the chewing cycle and the amount of

opening had the least error, and the amount of lateral excursion and

jaw-muscle EMG magnitudes had the most.

IRWIN BECKER et al (1999) 4 8 measured the effect of a prefabricated

anterior bite stop on the electromyographic activity of anterior

temporalis, posterior temporalis, masseter and anterior diagnostic

during clenching, and grinding. Prefabricated anterior bite stop was

fabricated for 30 subjects. Electromyographic activity was measured

during clenching and grinding both with and without the anterior bite

stop. The bite stop had a significant effect in decreasing

electromyographic activity for both clenching and grinding for

temporalis and masseter muscles.

GLENN T. CLARK et al (1999) 4 9 summarized the research in which

experimental occlusal interferences had been placed on the teeth of


26

animals and human volunteers. The outcome of these interferences was

analyzed according to their local pulp – periodontal, jaw function, or

bruxism effects. Experimental occlusal interferences in maximum

intercuspation had a deleterious effect on periodontal and pulp tissues

of the affected tooth. Experimental occlusal interferences that contact

only in a lateral jaw movement are infrequently harmful to jaw

function. Although occlusal therapy may be justified for reasons of

esthetics, gross occlusal instability, or dental disease, the data do not

exist showing that occlusal interferences are the cause of chronic jaw

dysfunction problems.

TORSTEN JEMT et al (2004) 5 0 evaluated the effect of two distinctly

different occlusal designs on the general chewing pattern as well as the

movement in the terminal part of chewing cycle. Chewing pattern was

registered by LED attached to on a mandibular tooth and on spectacle

frames as a reference. Test subjects received a canine protection

occlusion, and the chewing pattern was recorded after a 4 month

adaptation period. The occlusion was altered to group function, and a

second registration was made after 5 months. The results indicate that

the chewing pattern may be influenced by the type of occlusion

irrespective of the existence of the maxillary canines.

N. OKANO et al (2007)5 1 investigated the influence of experimentally

altered occlusal guidance on masti catory muscle activity.

Electromyography activities in the bilateral masseter, anteri or and

posterior temporalis were recorded during maximal clenching. They


27

concluded that EMG activity in the anterior temporalis significantly

increased in the simulated group function occlusion and the simulated

bilateral balanced occlusion compared with th e simulated cuspid

protected occlusion. The increased teeth contacts to the posterior

region altered the unilateral pattern of the anterior temporalis activity

to the bilateral pattern, while that of masseter activity remained

unchanged. They suggest that group function occlusion and balancing

contact may allow a large parafunctional activity. They also indicate

that canine protected occlusion may reduce the parafunctional activity,

at least in a controlled experiment.

PAUL H. POKORNY et al (2008)5 2 Reviewing the literature and

searching for a scientific basis for occlusion leads to the realization

that the earliest reports were predicated upon years of successful

clinical observations or subjective experiences and closely held

anecdotal opinions that were sometimes associated with proprietary

mechanical instrumentation. Occlus al concepts were initially

formulated and developed for the eden tulous patient requiring

prosthetic rehabilitat ion. Following the exercise of these concepts in

clinical practice, they were refined and applied to the fixed

prosthodontic reconstruction of the natural dentition. While

gnathological concepts offer a structured methodology for

prosthodontic procedures, further research is needed to corroborate

current occlusal treatment approaches.


28

YU-YING CHEN et al (2008)5 3 this review of the literature reveals

that the healthy anterior teeth and/or natural canines are present, the

occlusion allows the teeth to distribute horizontal forces in excursions,

while the posterior teeth d isocclude any excursion. Anterior bite force

measurements and electromyographic studies also showed that the

stomatognathic system elicits significantly less force when the

posterior segments are not in contact in the lateral mandibular

excursion. According to Weinberg and Kruger with every 10° change in

the angle of disclusion, there is a 30% difference in load. They

suggested that the anterior guidance of implant - supported prostheses

should be as shallow as possible to avoid greater forces on the anterio r

implants by steeper incisal guiding angles.

MARIA JOSE CAMPILLO et al (2008)5 4 conducted a study to

determine the effect of the occlusal scheme on masseter EMG activity

at different jaw posture tasks. They included 30 healthy subjects with

natural dentit ion and bilateral molar support, 15 with bilateral canine

guidance, and 15 with bilateral group function. They concluded that,

experimentally gained data about EMG pattern of masseter muscles

during the jaw posture tasks studied promote a better understand ing of

the control strategies of the motor system. They suggested that canine

guidance and group function have a similar effect on masseter muscles

to avoid excessive muscular activity during laterotrusive occlusal

excursion.


29

NEETA PASRICHA et al (2012)5 5 this review of the literature reveals

that , In order for canine-protected occlusion to function, the anterior

teeth must be healthy. The patient’s existing occlusal scheme should

not be altered unless such alterations are required to correct a non

physiological dentit ion. If the restoration must re establish lateral

guidance canine- protected occlusion is preferred when remaining

canines are present and not periodontally compromised. Canine

guidance reduces horizontal forces on posterior teeth and promotes a

more vertical chewing cycle.

VENUS SIDANA et al (2012)5 6 this review of the literature reveals

that , Group function is most often encountered in elderly. With this

type of occlusion it is possible to achieve harmonious balance of all

involved structures including muscles, temporomandibular joint, teeth

and their occlusal anatomy. Furthermore a patient with parafunctional

bruxing habit might welcome the lateral excursive freedom of group

function. Consideration of a patient’s chewing pa ttern, craniofacial

morphology, static occlusion type current oral health status

parafunctional habits might provide the important and relevant

information about the suitable functional occlusion type for each

patient.

SAPKOTA et al (2014)5 7 conducted a study to find out the frequency

of occlusal pattern in lateral position and compared the accuracy of

shim-stock and articulating paper. They concluded that the majority of

the contact pattern were group function was about 84% with shim stock


30

and 94% with articulating paper. Also shim stock exhibits superior

accuracy and reliabil ity.

JAAFAR ABDUO et al (2015)5 8 this review of the literature reveals

that , 1. There are some differences between the different lateral

occlusion schemes in relation t o parafunctional muscle activities and

the magnitude of mandibular movement. However, physiologic function

and patient acceptance appear to be minimally in fluenced by the lateral

occlusion scheme. Nevertheless, the clinical significance of the

reported differences cannot be confirmed since the long -term studies

have confirmed the suitability of CGO and GFO. CGO or GFO are

equally acceptable when restoring denti tion. Multidirectional freedom

of mandibular movement appears to be physiological . The evidence

supports a flexible principle of occlusion rather than a preconceived

occlusion theory. Similar lateral occlusion principles can be considered

for implant prosthesis.

Materials and methods

31

STUDY DESIGN:

The present study was performed to evaluate the elevator (Masseter,

Temporalis) muscle activity using Electromyography with the help of surface

electrodes when the patients were restored with fixed partial dentures in group

function occlusion and canine guided occlusion.

PLACE OF STUDY:

1. Department of Prosthodontics, Tamil Nadu Government Dental College &

Hospital, Chennai.

2. Institute of Neurology, Madras medical College & Rajiv Gandhi Government

General Hospital, Chennai.

ETHICAL COMMITTE APPROVEL:

The study was done after obtaining approval from the Institutional Ethical Committee.

ARMAMENTARIUM USED IN THIS STUDY:

ARMAMENTARIUM FOR EXAMINATION:

1. Mouth mirror

2. Explorer

3. Periodontal probe

4. Kidney tray

5. Disposable Gloves

6. Mask

7. IOPA

8. OPG


32

ARMAMENTARIUM FOR MAKING DIAGNOSTIC MODEL:

1. Rubber Bowl and Alginate Spatula

2. Alginate

3. Stainless steel perforated dentulous stock trays

4. Dental stone

5. Dental plaster

6. Plaster spatula

ARMAMENTARIUM FOR TOOTH PREPARATION:

1. Injection Local Anesthesia (Lignocaine)

2. Sterile 3ml disposable syringe

3. Airotor Hand piece

4. Diamond points

5. Retraction cord

ARMAMENTARIUM FOR IMPRESSION MAKING:

1. Putty elastomeric impression material

2. Light body elastomeric impression material

3. Tray adhesives

4. Spacer (cellophane Sheet)

5. Metal Stock trays

6. Bite registration material

7. Triple tray

ARMAMENTARIUM FOR LAB PROCEDURE:

1. Die stone

2. Die pin


33

3. Die cutting saw

4. Semi- Adjustable articulator (HANAU WIDE VUE II)

5. Die spacer

6. Inlay wax

7. Casting ring

8. Investment material

9. Burnout machine

10. Casting machine

11. Metal pellets

12. Sand blasting machine

13. Metal trimmers

14. Micro motor

15. Cold mold seal

16. Auto polymerizing resin (tooth colored)

ARMAMENTARIUM TO DETERMINE ELEVATOR MUSCLE ACTIVITY:

1. Electromyograph-EMG 4 CHANNEL EMG.NP.NCS system; Allengers

SCORPIO-4P model, including hard ware and soft ware systems. (Allengers

Medical Systems Ltd., Chandigarh, India).

2. Active (Black colour), and passive (Red colour) silver-silver electrodes

3. Ground (Green) electrode

4. Electrode Gel

5. Surgical spirit (Hy-Chem Lab, Hyderabad)

6. Micropore surgical tape (3M, Europe)


34

GROUPING OF PATIENTS:

This clinical study was based on use of group function occlusion and canine

guided occlusion in fixed partial denture patients. Hence for each patient two different

occlusal types of fixed partial denture were cemented in one week interval. A total of

10 patients were selected.

Group A- Fixed partial denture with group function occlusion (10 samples)

Group B- Fixed partial denture with canine guided occlusion (10 samples)

GENDER:

Male and Female patients aged between 25 to 45 years were selected.

SAMPLE SIZE:

Total number of patients: 10

CRITERIA FOR SELECTION:

INCLUSION CRITERIA:

1. FPD preparation for replacing of missing two maxillary premolars

which involves canine and first molar as abutments on one side was

selected.

2. Intact dentition opposing the edentulous space (any restoration if

required was completed before the study was undertaken).

3. The incisal guidance should be acceptable, if not it was corrected either

by occlusal equilibration or by restorative procedures.

4. Elimination of posterior interferences and finally achieving good

occlusal harmony


35

5. Presence of good periodontal health.

EXCLUSION CRITERIA:

1. Loss of anterior guidance, which cannot be corrected without extensive

restorative procedures were excluded.

2. Multiple tooth missing (long span)

3. Poor periodontal health

4. Missing opposing teeth.

5. Medically compromised and debilitating patients.

6. Pregnant mothers

7. Mentally challenged patients

8. Rotated, supra erupted teeth

9. Recently extracted /unhealed edentulous space

10. Uncorrectable occlusal discrepancies

11. Teeth in cross bite

12. Patients having severely attrited teeth.

13. Patients lacking proper neuromuscular control

14. Patients having deep bite

15. Patients with history of orthodontic treatment

16. Patients having disharmony in occlusion and TMJ dysfunction.


36

FLOW CHART

FIXED PARTIAL DENTURE PATIENTS

Group B

10 Samples

Group A

10 Samples

FPD (Group function occlusion) FPD (Canine guided occlusion)

After 1 week Post cementation After 1 week Post cementation

STATISTICAL ANALYSIS

RESULTS

Maximum Voluntary

Clenching

Lateral Excursion

towards restored side

Measuring Masseter

Muscle Activity

Using EMG

Measuring Temporalis

Muscle Activity

Using EMG

Maximum Voluntary

Clenching

Lateral Excursion

towards restored side

Measuring Masseter

Muscle Activity

using EMG

Measuring

Temporalis Muscle

Activity Using EMG


37

MATERIALS USED IN THIS STUDY

S.No Commercial

name

Form of the Material Manufacturer

Details

1. Vignette Alginate Densply, USA

2. Variotime

Easy Putty

Polyvinyl siloxane putty

impression material

Heraeus, Germany

3. Variotime

Light flow

Polyvinyl siloxane light

flow impression

material

Heraeus, Germany

4. Futar D Vinyl polysiloxane bite

registration material

Kettenbach & co.

Germany

5. Templute Eugenol free temporary

luting cement

Prime dental

products P.Ltd,

Thane

6. Pearlstone Type IV Die stone Asian chemicals,

Gujarat .

7. Denstone Type III Dental stone Pankaj Ent.

Mandideep (M.P)

8. Uniwax Crown wax Normal, India

9. Metavest Phosphate bonded

investment material

Delta,Germany

10. Omin-Pak #000 Knitted retraction

cord

Ossum health care

P.Ltd, Bangalore

11. Mani-Dia Burs Diamond abrasives Mani, INC, Japan

12. Pana-Air Airotor hand piece NSK, Japan

13. DPI Self-cure

tooth

moulding

powder

Auto polymerising resin DPI, India

14. Hanau Wide

Vue II

Semi adjustable Arcon

type articulator

Whipmix, USA

15. Electromyograph-

EMG 4

CHANNEL

EMG.NP.NCS

system;

Allengers SCORPIO-4P

model

Allengers Medical

Systems Ltd.,

Chandigarh, India


38

METHODOLOGY:

1. Making diagnostic impressions and diagnostic articulation

2. Tooth preparation and impression making

3. Provisional restoration

4. Articulation of Working cast with removable die

5. Fabrication of fixed partial dentures

a. FPD with group function occlusion

b. FPD with canine guided occlusion

6. Preparation of patient for Electromyographic Assessment

a. Landmarks for electrode placement for Temporalis muscle

b. Landmarks for electrode placement for Masseter muscle

7. Electromyographic recording procedure

a. Group A patients (group function occlusion)

(i) EMG Recordings of Temporalis and Masseter

Muscles during Clenching on the restored side.

(ii) EMG Recordings of Temporalis and Masseter

Muscles during Lateral Eccentric movement

towards the restored side

b. Group B patients (canine guided occlusion)

(i) EMG Recordings of Temporalis and Masseter

Muscles during Clenching on the restored side.

(ii) EMG Recordings of Temporalis and Masseter

Muscles during Lateral Eccentric movement

towards the restored side

8. Statist ical analysis


39

SOURCE OF DATA:

Patients reporting to the Department of Prosthodontics, Tamil Nadu

Government dental College and Hospital, Chennai were selected. The purpose and

objective of the study was explained to all the patients and both the informed and

written consent were obtained from all the patients.

1. MAKING DIAGNOSTIC IMPRESSIONS AND DIAGNOSTIC

ARTICULATION: In the initial appointment, preliminary impressions were

made with irreversible hydrocolloid impression material (Vignette, Dentsply,

India) using stainless steel perforated dentulous stock trays. Diagnostic casts

were obtained by pouring Type III dental stone. The diagnostic casts were

mounted on a semi adjustable articulator (HANAU WIDE VUE II) using a

face-bow transfer (HANAU WIDE VUE II) and centric relation record with

polyviniyal siloxane bite registration material (Futar D, Kettenbach & Co.

Germany).

2. TOOTH PREPARATION: After proper examination and analysis,

premature contacts were eliminated and occlusal harmony was established.

Putty index of the diagnostic cast was made involving the tooth to be prepared

and the teeth adjacent to it, for verification of abutment tooth reduction. Test

dose of local anesthesia was given to rule out allergy. Under local anaesthesia,

Tooth preparation was done with diamond points and airotor hand piece after

depth orientation grooves were made. Reductions of the occlusal and facial

surfaces were done to 1.5mm and lingual and proximal surfaces to 1mm.

Equigingival margin of shoulder with bevel was made in the facial aspect and


40

chamfer margin in the proximal and lingual aspects. Twisted Retraction cord

{Omin-pak ( #000)} was placed and subsequently two stage putty and light

body impression technique was followed for the fabrication of wax pattern

and castings. Second impression was made with irreversible hydrocolloid

impression material for the fabrication of the provisional restoration.

3. FABRICATION OF PROVISIONAL RESTORATION AND

CEMENTATION: Type- III dental stone was poured and cast was obtained

from the impression made with the irreversible hydrocolloid after tooth

preparation. In the study model the denture tooth was placed in wax in the

edentulous area and putty index was made. The index was used to fabricate the

provisional restoration using tooth colored auto polymerizing resin. Trimming,

polishing was done after verification of occlusal morphology and the

provisional restoration was cemented with Eugenol free temporary luting

cement (Templute, Prime Dental Products).

4. ARTICULATION OF WORKING CAST WITH REMOVABLE DIE:

The working casts were obtained by pouring Type IV die stone from the

impression made with elastomeric impression material, later die pins were

placed, base were made and die preparation was done. Face bow transfer was

done and maxillary cast was mounted in the semi-adjustable articulator,

mandibular cast was articulated according to the maximum intercuspation

record using triple tray and vinyl polysiloxane impression material.

Programming of articulator was done using protrusive interocclusal record.


41

5. FABRICATION OF FIXED PARTIAL DENTURE:

a.FPD with group function occlusion Die spacer was applied to the prepared

teeth and wax pattern was fabricated using Inlay wax, with normal occlusal

anatomy which was later carved and finished. The length of the maxillary

buccal cusps was determined by moving the articulator into protrusive and a

working lateral excursion. Upper and lower posteriors were checked whether

that they made contact along with cuspids on the working side and established

the group function occlusion.

Wax pattern was sprued, invested and casting was done. The casting

was divested, sandblasted with 50µm alumina after the sprues were cut. They

were subsequently trimmed with the metal trimmers and polishing done with

the polishing kit and rouge.

The finished castings were inserted in the patient's mouth for fit and accuracy.

The surface of a coping that were to receive porcelain was again sand

blasted with 50 micrometer aluminum oxide. The opaque porcelain was

applied to the copings followed by dentin and enamel porcelain and firing was

done. Trimming was done and checked in the semi-adjustable articulator by

moving the articulator into protrusive and a working lateral excursion. Upper

and lower posteriors were checked that they made contact along with cuspids

on the working side and established the group function occlusion.

Bisque trial was done in the patient mouth. The patients were

instructed to close on the posterior teeth. They were then made

to move their mandible laterally to the side till the cusp tip of

the lower canine contacted the cusp tip of upper canine. At this


42

position observations were made to ensure contacts between

upper and lower posteriors along with the cuspids on the working

side and established the group function occlusion . Final glaze

was done.

(b) FPD with canine guided occlusion Same procedure was followed for

casting. Checking was done with the semi-adjustable articulator by moving the

articulator into protrusive and a working lateral excursion. Canine guided

occlusion was developed by shortening of the maxillary buccal cusp tips and

increase the lingual contour of the maxillary canine surface, so that the tip

barely misses the opposing mandibular posterior cusp tips on the side of the

working lateral mandibular excursion on the side of restoration.

Bisque trial was done in the patient mouth. The patients were

instructed to close on the posterior teeth. They were then made

to move their mandible laterally the side till the cusp tip of

lower canine contacted the cusp tip of upper canine. At this

position observation were made to ensure only the cuspids were

contacting and checked for the disclusion of the posterior teeth

of the working side and non-working side. Final glaze was done. .

6. Preparation of patient for electromyographic study: Prior to

recording EMG of muscle, the patient s were made to sit in an

upright position and the skin was cleaned with surgical spirit .

Male patients were to be requested to shave. Electrode gel was applied and

electrodes were placed.


43

a. Landmarks: Temporalis Muscle : A line along the

Frankfort horizontal plane was drawn from the tragus to the

infra orbitale. A point was then marked on the line 50 mm

from the tragus. The electrodes for the temporal muscle was

placed with the first electrode 20 mm vertically above the

point and the second electrode was aligned 20 mm (center-to-

center) from the first electrode in the direction of the muscle

fibers.

b. Landmarks: Masseter Muscle The first electrode over

the masseter muscle was placed 25 mm vertically below the

point. The second electrode was aligned in the general

direction of the muscle fibers at a distance of 20 mm (center-

to-center) from the first electrode. A common ground electrode

was adhered onto the forehead of the patients. Electrode

alignments were assisted by palpation during voluntary

clenching and relaxation in the intercuspal position.

7. ELECTROMYOGRAPHY RECORDING PROCEDURE:

a. Group A patients (Group function occlusion) The EMG

recordings were made in the following pattern for group

function occlusion. Fixed partial denture with group function

occlusion was first cemented using Eugenol free temporary

luting cement . After one week EMG recordings were done.


44

i .EMG Recordings of Temporalis and Masseter Muscle during

Clenching on the restored side : After the electrodes were attached,

the patients were instructed to clench maximally. The EMG activity

recording for the temporalis and masseter muscle in each of the

following series took place during maximal voluntary clen ching with in

a time period of 4 seconds and the results obtained were tabulated.

i i .EMG Recording of Temporalis and Masseter Muscle during

Lateral Eccentric movement towards the restored side: After the

electrodes were attached, the patients were instructed to move the

mandible laterally towards the restored side until the desired lateral

jaw position was reached (i.e., when the maxillary and mandibular

canines were in tip to tip position). The EMG activity recording for

temporalis and masseter muscle in each of the following series took

place during lateral eccentric movement within a time period of 4

seconds and the results obtained were tabulated.

(b).Group B patients (canine guided occlusion) : Fixed partial denture

with canine guided occlusion was cemented using Eugenol free

temporary luting cement to the same patients. EMG recording

procedure was performed after one week. The EMG recordings were

made in the same pattern as for group function, such as

I. EMG Recording of Temporalis and Masseter Muscle during

Clenching on the restored side.


45

II.EMG Recording of Temporalis and Masseter Muscle during

Lateral Eccentric movement towards the restored side.

8. Statistical analysis : The data was quantitative and followed normal

distribution, parametric test of significance was employed. The mean

Electromyographic values of masseter and temporalis during clenching and

lateral excursion were compared using Independent sample T test. All analysis

were done using SPSS software (version 19 IBM). P value of < 0.05 was

considered to be statistically significant.

Photographs

1.Materials and Armamentarium used during diagnostic stage

2. Materials and Armamentarium used during diagnostic

mounting and face bow transfer

Photographs

3. Materials and Armamentarium used during Tooth

preparation, Impression and Temporization

4. Materials and Armamentarium used during Die

preparation, Wax pattern fabrication and Casting.

Photographs

5. Extra oral view 6. Pre-OP Intra oral view

7. Occlusal view

Maxillary Arch 8. Occlusal view

Mandibular Arch

10. Diagnostic Cast 9.Diagnostic Impression

Photographs

11. Diagnostic Articulation 12.Lingual half of the Index is

Positioned to check its Accuracy

13.Gingival half of the Index is

Positioned to check its Accuracy

14.Lingual half of the index over the

preparation to check Occlusal reduction

15.Gingival half of the index over the

preparation to check Labial reduction

16.Tooth preparation & Retraction

cord placement- Front view

Photographs

17.Tooth preparation & Retraction

cord placement- Occlusal view

18.Final Master Impression & Alginate

Impression

19.Working Cast for

Provisionalization.

20.Putty index for

Provisional Restoration.

21.Temporization 22. Die preparation in Master

cast

Photographs

23.Facebow Transfer 24.Triple tray & Maximum

Intercuspation Record

25.Articulation done for

fabrication of restorartion

26.Wax Pattern – Occlusal

view

27.Wax Pattern for CANINE

GUIDED OCCLUSION

28.Wax Pattern for GROUP

FUNCTION OCCLUSION

Photographs

29.Metal Coping – Occlusal

view

30.Metal Coping for CANINE

GUIDED OCCLUSION

31.Metal coping for GROUP

FUNCTION OCCLUSION 32.Metal Trial in Patient mouth

33.Metal trial – Occlusal view

34.Finished Metal Ceramic FPD

with GROUP FUNCTION &

CANINE GUIDED OCCLUSION

Photographs

35.Metal ceramic restoration for

GROUP FUNCTION OCCLUSION

36.Metal Ceramic restoration for


37.Non-Working Interferences

are relieved in Articulator

38.Metal Ceramic restoration checked in

patient mouth at maximum Intercuspation

39.Metal Ceramic Restoration

in Patient mouth-Occlusal view

40.GROUP FUNCTION OCCLUSION

achieved in WORKING SIDE

Photographs

41.Non-Working Interferences

was checked and relieved.

mouth

42.CANINE GUIDED OCCLUSION

achieved in WORKING SIDE

43.Electromyographic Unit 44.Electromyographic Software

45.Positive, Negative &

Ground Electrodes 46.EMG 4 Channel Amplifier Box

Photographs

47.Placement of surface electrodes to

record Masseter muscle activity

48.Placement of surface electrodes to

record Temporalis muscle activity

49.Base line Readings Before

Activity

50. EMG Recordings during

movement

Results

46

RESULTS

The following results were obtained from this study which evaluated the

activity of Elevator muscles (Masseter and Temporalis) in patients restored with Group

function occlusion and Canine guided occlusion.

Each of the ten patients were divided into two groups as Group A,

restored with Fixed partial denture with group function occlusion and Group B,

restored with Fixed partial denture with canine guided occlusion. Elevator muscle

activity was recorded using Electromyography.

The mean and standard deviation for Group A & Group B samples are

shown in the following tables with bar diagrams. Descriptive statistics was calculated

and expressed in terms of mean and standard deviation.

Since the data was quantitative and followed normal distribution,

parametric test of significance was employed. The mean Electromyographic values of

masseter and temporalis during clenching and lateral excursion were compared using

Independent sample T test. All analysis were done using SPSS software (version 19

IBM). P value of < 0.05 was considered to be statistically significant.

Results

47

TABLE 1: EMG Values of Masseter and Temporalis muscles during

Clenching in Group function and Canine guided occlusion on the

Restored side.

VARIABLES

N

Group Function

Occlusion

Canine

Guided

Occlusion

Mean

Difference

P value

Mean S.D Mean S.D

Masseter 10 415.60 20.48 418.80 26.63 3.20 0.767

Temporalis 10 332.90 36.47 339.70 37.17 6.80 0.685

TABLE 2: EMG Values of Masseter and Temporalis muscles during

Lateral Excursion in Group function and Canine guided

occlusion on the restored side.

VARIABLES

N

Group Function

Occlusion

Canine

Guided

Occlusion

Mean

Difference

P value

Mean S.D Mean S.D

Masseter 10 100.00 27.94 56.40 5.27 43.60 <0.001

Temporalis 10 124.90 26.31 77.20 9.57 47.70 <0.001

Results

48

Interpretation of the results

Comparison of group function and Canine guided occlusion of Masseter and

Temporalis muscle during clenching on the restored side.

Activity of Masseter and Temporalis between Group A and Group B were

compared by using the values of mean and standard deviation & P values. The results

are presented in Table - 1

From the result it was observed:

In group function occlusion the mean EMG value for masseter muscle

during clenching was 415.60 ± 20.48, whereas for canine guided occlusion it was

418.80 ± 26.63. The mean difference between the two types of occlusion was 3.20 and

this difference was found to be statistically not significant with the P value of 0.767.

For temporalis muscle, the mean EMG value in group function

occlusion during clenching was 332.90 ± 36.47, whereas for canine guided occlusion it

was 339.70 ± 37.17. The mean difference between the two types of occlusion was 6.80

and this difference was found to be statistically not significant with the P value of

0.685.

This denotes, the elevator muscle (Masseter & Temporalis) activities

was nearly the same in both the occlusal schemes during clenching.

Results

49

Comparison of group function and Canine guided occlusion of Masseter and

Temporalis muscle during Lateral excursion towards the restored side.

Activity of Masseter and Temporalis between Group A and Group B

were compared by using the values of mean and standard deviation & P values. The

results are presented in Table – 2

From the result it was observed:


during lateral excursion was 100.00 ± 27.94, whereas for canine guided occlusion it

was 56.40 ± 5.27. The mean difference between the two types of occlusion was 43.60

and this difference was found to be statistically significant with the P value of < 0.001.

For temporalis muscle, the mean EMG value in group function

occlusion during lateral excursion was 124.90 ± 26.31, whereas for canine guided

occlusion it was 77.20 ± 9.57. The mean difference between the two types of occlusion

was 47.70 and this difference was found to be statistically significant with the P value

of < 0.001.

This denotes, the elevator muscle (Masseter & Temporalis) activities are

greatly reduced in Canine guided occlusion when compared to that of Group function

occlusion during lateral excursion towards the restored side.

Bar diagrams

Fig : 1 Comparison between Group function and Canine guided

Occlusion of Masseter muscle during clenching and lateral


Fig : 2 Comparison between Group function and Canine guided

Occlusion of Temporalis muscle during clenching and lateral


0

50

100

150

200

250

300

350

400

450

CLENCHING LATERAL EXCURSION

EMG

Me

an v

alu

es

MASSETER MUSCLE ACTIVITY

GROUP FUNCTION CANINE GUIDED

0

50

100

150

200

250

300

350

400

CLENCHING LATERAL EXCURSION

EMG

Me

an v

alu

es

TEMPORALIS MUSCLE ACTIVITY


Bar diagrams

Fig-3 Comparison of Group function and Canine guided occlusion

during Maximum Voluntary clenching of Masseter and

Temporalis.

Fig-4 Comparison of Group function and Canine guided occlusion

during Lateral excursion of Masseter and Temporalis.

0

50

100

150

200

250

300

350

400

450

MASSETER TEMPORALIS

EMG

Me

an v

alu

es

MAXIMUM VOLUNTARY CLENCHING


0

20

40

60

80

100

120

140

MASSETER TEMPORALIS

EMG

Me

an v

alu

es

LATERAL EXCURSION


Discussion

50

DISCUSSION

Craniomandibular function is based on the complex and interrelated

components comprising the biomechanics and morphology of the muscles, joints, teeth,

and the neuromuscular system. The major reason for dentistry to deal with masticatory

muscle function is the significance of these muscles in the natural function and the

functional disorders of the craniomandibular system. There is a definitive association

between the occlusion and the outcome of the action of the masticatory muscles that is

the functional jaw movements.

Anterior guidance is essential for the harmonious functional relationship

with the masticatory system. An understanding of the mechanical principles governing

the anterior guidance can minimize trauma to the stomatognathic system.

Schuyler (1963)59 defined incisal guidance as the influence on the

mandibular movements guided by the contacting surfaces of the maxillary and

mandibular anterior teeth.

According to Angelo D' Amico(1961)3 a desirable horizontal overlap of

maxillary incisors and canines is important to prevent the attrition of opposing

premolars and molars as they can help to avoid the horizontal vector forces to the

periodontium .

Stuart and Stallard (1969)60 also observed this phenomenon and

therefore developed anterior guidance as part of the gnathological concept in mutually

protected articulation. According to the philosophy of gnathology, the anterior teeth

Discussion

51

protect the posterior teeth in eccentric movements of the mandible and the posterior

teeth should protect the anterior teeth in maximum intercuspation, known as mutually

protected articulation.

Canine protection and group function have been used for classification

of occlusal contact patterns in lateral excursions in natural dentition.

According to Robert Crum et al (1972)16, “the success or failure of a

prosthodontic restoration depends upon the integration of proper proprioceptive

feedback and motor responses. Accordingly anterior teeth are much more sensitive than

posterior teeth. So retaining anterior teeth as abutment for the prosthesis assumes a

greater importance”.

The present study was conducted to find out which of these two types of

occlusion generated through fabrication of four unit fixed partial dentures using canine

as an abutment leads to decreased elevator muscle activity during clenching and lateral

excursions using Electromyography. According to the predetermined selection criteria

10 partially edentulous patients were selected for this study. Though usually fixed

partial dentures are fabricated in group function occlusion, a deviation from the

customary occlusion that is incorporating canine protected occlusion cannot be taken

into account until it is proved through many studies. Ours is one such attempt.

The study of electrical activity of the muscles was first introduced by

Erb to provide information regarding the functioning of its motor units.

Electromyography was a sensitive tool widely used by R.E. Moyers in 1949 to analyze

the behavior of the masticatory muscles in patients with craniomandibular disorders.

Discussion

52

Y.Yamada et al (1985)31 analyzed the utilization of electromyograms in

clinical dentistry. It is a machine used for real time neurophysiologic data acquisition

and analysis system with a versatile hardware and software combination. It permits the

analysis of jaw reflexes and generation of a hard copy output in 31/2 minutes.

Electromyography (EMG) is a technique for evaluating and recording

the electrical activity produced by skeletal muscles. EMG is performed using an

electromyograph to produce a record called an electromyogram. An electromyograph

detects the electric potential generated by muscle cells, when these cells are electrically

or neurologically activated.

The basic functional entity of the muscles is the motor unit which is

comprised of the motoneuron, its axon and the muscle fibers innervated by branches of

the axon. This muscle fiber contracts when the action potentials of the motor nerve

supplying it reaches a depolarization threshold. The depolarization generates an

electromagnetic field which is measured as a very small voltage known as EMG.

ELECTRODE:

In EMG, an electrode is an electric conductor that conveys the electric

current from the biological myoelectric source to the electronic amplifier. There are

two kinds of EMG, they are;

1. Non-invasive or Surface electrodes

2. Invasive or Needle electrodes

https://en.wikipedia.org/wiki/Skeletal_muscles

https://en.wikipedia.org/wiki/Electric_potential

https://en.wikipedia.org/wiki/Cell_%28biology%29

Discussion

53

Surface EMG assesses muscle function by recording muscle activity

from the surface above the muscle on the skin. Invasive electrodes collect the EMG

from within the muscle and penetrate the skin surface.

MOTOR UNIT ACTION POTENTIAL:

A motor unit is defined as one motor neuron and all of the muscle fibers

it innervates. When a motor unit fires, the impulse (called an action potential) is carried

down the motor neuron to the muscle. The area where the nerve contacts the muscle is

called the neuromuscular junction, or the motor end plate. After the action potential is

transmitted across the neuromuscular junction, an action potential is generated in all of

the innervated muscle fibers of that particular motor unit. The sum of all this electrical

activity is called as a motor unit action potential (MUAP). This electro physiologic

activity from the multiple motor units is the signal typically evaluated during an EMG.

Amplitude is measured from the base line to the maximum height

observed in the wave and represented by microvolts. Duration is measured from the

distance between consecutive corresponding points of the wave.

The present study was concerned with the surface

electrodes, as only the superficial muscles (Temporalis and Masseter)

were taken for EMG study.

In this study surface electrodes were employed to determine the elevator

muscle activity. Though surface and needle electrodes can be used to find out the

muscle dynamics, Surface electrodes records the global activity of the muscles. They

https://en.wikipedia.org/wiki/Motor_unit

https://en.wikipedia.org/wiki/Neuron

https://en.wikipedia.org/wiki/Muscle_fibers

https://en.wikipedia.org/wiki/Action_potential

https://en.wikipedia.org/wiki/Neuromuscular_junction

https://en.wikipedia.org/wiki/Motor_end_plate

Discussion

54

are convenient and painless and are sufficient enough for evaluation of superficial

muscles.

Surface Electrodes

They are generally two small plates made of silver/silver

chloride which were placed over the muscles using key guidelines for

masseter and temporalis, (Stephen W. H. Yuen et al 1990)6 1 . A ground

electrode was placed onto the forehead of the patients. Electrodes were

attached to the skin by an electrode gel and adhesive tape.

EMG study was done during maximum voluntary clenching

and lateral excursion of the mandible towards the restored side in two

different occlusions in the masseter and temporalis muscles.

“Because isometric bite forces vary from individual to

individual, and from time to time in a single individual, measurements

were made through maximum voluntary isometric contractions

(clenches)”. (Stephen W. H. Yuen et al 1990) 6 1 .

Vittasalo and Komi (1975) 6 2 also showed that maximum

voluntary isometric contractions might be the best way to standardize

the test si tuations.

Comparison was made between the mean values and standard deviation

of EMG values between the group function and canine guided occlusion during

clenching and lateral excursion of masseter and temporalis muscles.

Discussion

55


during clenching was 415.60 ± 20.48, whereas for canine guided occlusion it was

418.80 ± 26.63. The mean difference between the two types of occlusion was 3.20 and

this difference was found to be statistically not significant with the P value of 0.767.

For temporalis muscle, the mean EMG value in group function occlusion during

clenching was 332.90 ± 36.47, whereas for canine guided occlusion it was 339.70 ±

37.17. The mean difference between the two types of occlusion was 6.80 and this

difference was found to be statistically not significant with the P value of 0.685.

In group function the mean EMG value for masseter muscle during

lateral excursion was 100.00 ± 27.94, whereas for canine guided occlusion it was 56.40

± 5.27. The mean difference between the two types of occlusion was 43.60 and this

difference was found to be statistically significant with the P value of < 0.001. For

temporalis muscle, the mean EMG value in group function occlusion during lateral

excursion was 124.90 ± 26.31, whereas for canine guided occlusion it was 77.20 ±

9.57. The mean difference between the two types of occlusion was 47.70 and this

difference was found to be statistically significant with the P value of < 0.001.

The results revealed that the EMG values recorded during laterotrusion

was significantly less in case of patient in whom fixed partial dentures were restored

using canine protected occlusion when compared to those in whom fixed partial

dentures were restored with group function occlusion. The elevator muscle (Masseter &

Temporalis) activities was nearly the same in both the occlusal schemes during

clenching.

Discussion

56

This result of this study can be correlated from the following authors.

Arturo Manns et al (1987)33 stated in his study that the reduction in the

elevator muscle activity was greater in canine protected occlusion as the pressure is

concentrated in a small periodontal surface area.

U. C. Belser et al (1985)30 put forward that canine guided occlusion do

not significantly alter muscle activity during mastication but it significantly reduces

the muscle activity during parafunctional clenching.

Ronald J. Shupe et al (1984)28 tried to create canine protected

occlusion in a maxillary occlusal splint using heat cured acrylic resin in maxillary teeth.

The splint had a minimal palatal coverage and a minimal increase in vertical dimension

of occlusion. Results revealed that the forces generated to the posterior teeth were

reduced.

Keith E. Thayer (1981)25 used metal canine risers which were bonded

to the lingual surface of maxillary canine teeth without any tooth preparation. After two

years of follow up it was proved to be beneficial in eliminating the bruxism and

clenching habits.

Gary Robert Goldstein (1979)20 found out that the teeth of mouths

having canine protected occlusion had lower mean periodontal disease index scores

than in those with progressive disclusion or with group function occlusion.

Moller (1981)63 suggested that jaw muscle activity is dependent on the

number of occlusal contacts.

Discussion

57

Van Steenberghe and De Vries (1978)64 showed that an increase in the

number of teeth that come into contact on both sides of the arch results in an increase of

the force that can be developed between the jaws.

Williamson and Lundquist (1993)26 observed a reduction in EMG

activity of the temporal and masseter muscles in patients with canine guidance when

compared to with group function occlusion. These investigators concluded that only

with appropriate anterior guidance could the EMG activity of the muscles be reduced.

Ronald J Shupe et al (1984)28 also looked at EMG activity of the

masticatory muscles. They compared the effects of flat canine guidance, group

function, and steep canine guidance on the EMG activity of the masseter and temporal

muscles. They found less EMG activity with steep canine guidance, supporting the

findings of Williamson and Lundquist.

According to Gar S. Graham et al (1988)35 study the EMG activity of

the masseter and anterior part of the temporal muscles was reduced with canine

protected occlusion and first molar guidance during lateral excursive movement and

excursive position clenching.

According to Jemt et al, (2004)50 in a case series crossover study of 5

individuals treated with a maxillary implant-supported FPD and opposing mandibular

dentition, observed that lateral displacement and total displacement of mandible was

greater with group function occlusion than with canine-protected occlusion.

Discussion

58

A.C. Akoren et al (1995)43 observed that canine guidance compared

with group function occlusion caused a greater electromyographic activity reduction

of anterior temporal muscle during laterotrusive sliding while the teeth were in

contact.

N.Okano et al (2007)51 stated that the EMG activity in the anterior

temporalis significantly increased in the simulated group function and the simulated

bilateral balanced occlusion compared with the simulated cuspid guided occlusion.

D’Amico (1961)3 stated that canine protection favors the vertical

chewing pattern and prevents the wear of teeth.

Ash and Ramjford (1996)65 observed that a steep canine rise on

Michigan splint can reduce the EMG activity of masseter and temporalis muscles.

Murray (2001)66 explained a technique for the provision of canine riser

restoration, which deliberately altered the cuspal inclines in canine teeth to provide

canine protected occlusion. He believed that these restorations may help to control

excessive loading, limit the tooth wear, and assist in management of

Temporomandibular joint disorders.

Jiang, Su et al (2010)67 conducted a study to evaluate the clinical

treatment effect on bruxism using group functional occlusal splint and canine guided

occlusal splint. The successful rate of treatment of bruxism was 83.33% in canine

guided occlusion and 79.1% with functional splint.

Discussion

59

According to Henke and Friedrich (1999)68 the canine guided

occlusion decreased the lateral stresses on posterior teeth and is preferred over group

function occlusion for restoring and altering the anterior guidance.

Goldstein (1979)20 found the relationship of canine-protected occlusion

to periodontal index. The teeth of mouth having canine-protected occlusion had

significantly lower mean periodontal indices.

Summary and conclusion

60

SUMMARY AND CONCLUSION

This study has been formulated to evaluate the Electromyographic

activity of elevator muscles (Masseter & Temporalis) in lateral guidance with group

function and canine guided occlusion in patients who required restoration of canine and

posterior teeth.

For each of the 10 patients, two fixed partial dentures were fabricated

one with group function occlusion, the other with canine guided occlusal schemes. The

basic principles and recording procedures has been discussed. The obtained results

were subjected to statistical analysis.

From the analysis, following conclusions were drawn:

Highly significant reduction of EMG activity of elevator muscles (Masseter and

Temporalis) was observed during lateral excursion in Canine guided occlusion

when compared to that of Group function occlusion.

EMG activity of elevator muscles was nearly the same during clenching in both

the type of occlusal schemes.

When an entire occlusion is to be restored, reestablishment with canine guided

occlusion is preferred when remaining canines are present with good

periodontal support.

The EMG values obtained in this study can be taken as base line data for future

studies.

Summary and conclusion

61

“When bone and muscle war, muscle never loses” (Harry Sicher). “When

teeth and muscle war, muscle never loses” (Peter. E. Dawson)69.

From the above statements, it clearly shows that masticatory muscles

play a predominant role in stomatognathic system. So it is mandatory to follow this

guideline and not overlook the factor. At the same time any step taken which involves

this muscle must be cautious.

Technology remains useless unless used. To conclude, further studies in

the same outlook will serve the purpose of adding one more feather to the dental realm.

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Annexure

71

PARTICIPANT INFORMATION SHEET

Investigator: Dr.S.Elavarasan

Guide: Prof .Dr.K.VINAYAGAVEL, M.D.S.,

Title of the study: EVALUATION OF ELEVATOR MUSCLE ACTIVITY

USING ELECTROMYOGRAPHY IN PATIENTS RESTORED WITH FIXED

PARTIAL DENTURE IN GROUP FUNCTION OCCLUSION AND CANINE

GUIDED OCCLUSION

Name of the research institution: Tamilnadu Government Dental College &

Hospital, Chennai.

Purpose of the study: To find out the elevator (masseter, temporalis) muscle

activity using EMG with the help of surface electrodes will be done after

restoration with fixed partial dentures in group function occlusion and canine

guided occlusion.

Procedure: The following examination/investigation will be done for you.

Intra oral examination. Routine examination will be done using mouth

mirror and probe. Upper and lower diagnostic impression will be made.

IOPA radiographs will be taken.

For protection from X-rays, Lead Apron & Thyroid collars will be used.

Local anaesthesia will be given. Tooth preparation will be done followed

by impression will be made and temporary FPD will be cemented.

Two sets of FPD will be fabricated, one with group function occlusion and

another with canine guided occlusion. Surface Electromyography study

will be done in one week interval.

Risks of participation:

Risks :patient may be allergic to local anaesthesia ,test dose will be given to rule

out allergic reactions.

To prevent Iatrogenic pulp exposure diagnostic IOPA will taken and protocols for

biomechanical tooth preparation will be followed.

For protection from X-rays, Lead Apron & Thyroid collars will be used.

Confidentiality: The privacy of the patients in the research will be maintained

throughout the study. In the event of any publication or presentation resulting from

the research, no personally identifiable information will be shared.

Participant’s rights: Taking part in the study is voluntary. You are free to decide

whether to participate in the study or to withdraw at any time. Your decision will

not result in any loss of benefits to which you are otherwise entitled. The results

of this study will be intimated to you at the end of the study period or during the

study if anything is found abnormal which may aid in the management or

treatment.

Compensation: NIL

Annexure

72

Annexure

73

INFORMED CONSENT FORM

STUDY TITLE:

“EVALUATION OF ELEVATOR MUSCLE ACTIVITY USING

ELECTROMYOGRAPHY IN PATIENTS RESTORED WITH FIXED PARTIAL

DENTURE IN GROUP FUNCTION OCCLUSION AND CANINE GUIDED

OCCLUSION”

Name:

O.P.No:

Address: S. No:

Age / Sex:

Tel. no:

I, _____________________________________________________ age

________ years exercising my free power of choice, hereby give my consent

to be included as a participant in the study “Evaluation Of Elevator Muscle

Activity Using EMG In Patients Restored With Fixed Partial Denture In

Group Function Occlusion And Canine Guided Occlusion”

I agree to the following:

I have been informed to my satisfaction about the purpose of the

study and study procedures including investigations to monitor and

safeguard my body function.

I agree to undergo the procedure involved in the study process.

I have informed the doctor about all medications I have taken in the

recent past and those I am currently taking.

I agree to cooperate fully throughout the study period.

I hereby give permission to use my medical records for research

purpose. I am told that the investigating doctor and institution will

keep my identity confidential.

Name of the patient Signature / Thumb impression

Name of the investigator Signature

Date

Annexure

74

MASTER CHART

GROUP FUNCTION OCCLUSION

S.No

EMG VALUES OF

MASSETER MUSCLE

ACTIVITY

EMG VALUES OF

TEMPORALIS MUSCLE

ACTIVITY

MAXIMUM

VOLUNTARY

CLENCHING

LATERAL

EXCURSION

MAXIMUM

VOLUNTARY

CLENCHING

LATERAL

EXCURSION

1 422 74 310 167

2 445 71 385 96

3 388 79 280 98

4 396 134 295 137

5 398 82 345 95

6 415 128 346 138

7 402 69 289 101

8 438 138 352 141

9 410 119 361 154

10 442 106 366 122


S.No

EMG VALUES OF

MASSETER MUSCLE

ACTIVITY

EMG VALUES OF

TEMPORALIS

MUSCLE ACTIVITY

MAXIMUM

VOLUNTARY

CLENCHING

LATERAL

EXCURSION

MAXIMUM

VOLUNTARY

CLENCHING

LATERAL

EXCURSION

1 431 56 290 90

2 438 50 370 70

3 398 54 302 72

4 421 61 319 76

5 364 58 323 62

6 419 63 390 74

7 409 50 310 72

8 420 65 339 93

9 421 52 396 85

10 467 55 358 78

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